Modified colorants and inkjet ink compositions comprising modified colorants

ABSTRACT

The present invention relates to a modified colorant comprising a colorant having at least one polymer attached or adsorbed thereto. The polymer comprises at least one functional group, and various embodiments of the functional group are disclosed. For each of these embodiments, preferably the functional group has a defined calcium index value. Also disclosed are various uses for these modified colorants, including inkjet ink compositions. Thus, the present invention further relates to an inkjet ink composition comprising a) a liquid vehicle, b) at least one colorant, and c) at least one polymer comprising at least one functional group as described herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. application Ser. No.11/590,170 filed Oct. 31, 2006, which claims the benefit of U.S.Provisional Patent Application No. 60/731,721, filed Oct. 31, 2005, U.S.Provisional Patent Application No. 60/815,305, filed Jun. 21, 2006, U.S.Provisional Patent Application No. 60/815,327, filed Jun. 21, 2006, andU.S. Provisional Patent Application No. 60/815,326, filed Jun. 21, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to specific modified colorants and inkjetink compositions comprising these modified colorants.

2. Description of the Related Art

The surface of pigments contains a variety of different functionalgroups, and the types of groups present depend on the specific class ofpigment. Several methods have been developed for grafting materials and,in particular, polymers to the surface of these pigments. For example,it has been shown that polymers can be attached to carbon blackscontaining surface groups such as phenols and carboxyl groups. However,methods which rely on the inherent functionality of a pigment's surfacecannot be applied generally because not all pigments have the samespecific functional groups.

Methods for the preparation of modified pigment products have also beendeveloped which can provide a pigment with a variety of differentattached functional groups. For example, U.S. Pat. No. 5,851,280discloses methods for the attachment of organic groups onto pigmentsincluding, for example, attachment via a diazonium reaction wherein theorganic group is part of the diazonium salt.

Other methods to prepare modified pigments, including those havingattached polymeric groups, have also been described. For example, PCTPublication No. WO 01/51566 discloses methods of making a modifiedpigment by reacting a first chemical group and a second chemical groupto form a pigment having attached a third chemical group. Inkcompositions, including inkjet inks, containing these pigments are alsodescribed. In addition, U.S. Pat. Nos. 5,672,198, 5,922,118, 6,042,643,and 6,641,656 disclose modified pigments having various attached groups,including phosphonic acid groups.

While these methods provide modified pigments having attached groups,there remains a need for modified pigments having improved performanceproperties in compositions such as inkjet inks, thereby providingadvantageous alternatives to previous modified pigments.

SUMMARY OF THE INVENTION

The present invention relates to a modified colorant comprising acolorant having attached at least one polymeric group which comprises apolymer having at least one functional group. In a first embodiment, thefunctional group comprises at least one phosphonic acid group, partialester thereof, or salts thereof, and preferably comprises at least twophosphonic acid groups, partial esters thereof, or salts thereof. In asecond embodiment, the functional group comprises at least onehydroxamic acid group or salt thereof. In a third embodiment, thefunctional group comprises at least one heterocyclic group having atleast one OH group or salt thereof. In a fourth embodiment, thefunctional group comprises at least one phosphonic acid group or saltthereof and at least one second ionic, ionizable, or basic group. In afifth embodiment, the functional group comprises at least one heteroarylgroup having at least one carboxylic acid group or salt thereof. In asixth embodiment, the functional group comprises an aryl group having atleast one nitroso group and at least one OH group, or a salt thereof. Ina seventh embodiment, the functional group comprises an azoarene grouphaving at least one OH group, at least one NH₂ group, or at least one OHgroup and at least one NH₂ group and has the formula Ar¹—N═N—Ar²,wherein Ar¹ and Ar², which can be the same or different, are an arylenegroup or an aryl group and at least one of Ar¹ or Ar² is an arylenegroup. In an eighth embodiment, the functional group comprises an arylor alkyl polyacid group comprising at least two carboxylic acid groups,preferably at least three carboxylic acid groups. Preferably, theorganic group has a calcium index value greater than a calcium indexvalue of phenylphosphonic acid and more preferably greater than acalcium index value of 1,2,3-benzene tricarboxylic acid.

The present invention further relates to a modified colorant asdescribed herein that further comprises a second organic group that isdifferent from the polymeric group. The second organic group maycomprise at least one ionic group, at least one ionizable group, or amixture thereof. Also, the second organic group may be a polymericgroup.

The present invention further relates to inkjet ink compositioncomprising a) a liquid vehicle, b) at least one colorant, and c) atleast one polymer comprising at least one functional group as describedherein. The polymer may be as a separate additive or it may be eitherattached to or adsorbed on the colorant, such as a coating. The inkjetink compositions may further comprise a second modified pigmentcomprising a pigment having attached a second organic group differentfrom the organic group, such as at least one ionic group, at least oneionizable group, or a mixture thereof. The second organic group may alsobe a polymeric group.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to modified colorants having attached oradsorbed polymers and to inkjet ink compositions comprising colorantsand these polymers.

The modified colorant of the present invention comprises a colorant anda polymer. The polymer may be either a coating on the colorant or it maybe attached to the colorant. The colorant may be any colorant known toone skilled in the art, such as a dye (which is a soluble colorant) or apigment (which is an insoluble colorant). Preferably the colorant is anorganic colorant or a carbonaceous pigment and is either a pigment or adisperse dye (which is soluble in a solvent but is water insoluble).Most preferred are pigments.

The dye may be any of those known in the art, particularly those towhich at least one organic group may be attached. Thus, the dye can beselected from an acid dye, a basic dye, a direct dye, a disperse dye, ora reactive dye. Combinations of dyes may also be used in order to formdifferent shades. Examples of acid dye include, but are not limited to,Acid Red 18, Acid Red 27, Acid Red 52, Acid Red 249, Acid Red 289, AcidBlue 9, Acid Yellow 23, Acid Yellow 17, Acid Yellow 23, and Acid Black52. Examples of basic dyes include, but are not limited to, Basic Red 1,Basic Blue 3, and Basic Yellow 13. Examples of direct dyes include, butare not limited to, Direct Red 227, Direct Blue 86, Direct Blue 199,Direct Yellow 86, Direct Yellow 132, Direct Yellow 4, Direct Yellow 50,Direct Yellow 132, Direct Yellow 104, Direct Black 170, Direct Black 22,Direct Blue 199, Direct Black 19, and Direct Black 168. Examples ofreactive dyes include, but are not limited to, Reactive Red 180,Reactive Red 31, Reactive Red 29, Reactive Red 23, Reactive Red 120,Reactive Blue 49, Reactive Blue 25, Reactive Yellow 37, Reactive Black31, Reactive Black 8, Reactive Green 19, and Reactive Orange 84. Othertypes of dyes can also be used, including, for example, Yellow 104 andMagenta 377.

The pigment can be any type of pigment conventionally used by thoseskilled in the art, such as black pigments and other colored pigmentsincluding blue, black, brown, cyan, green, white, violet, magenta, red,orange, or yellow pigments. Mixtures of different pigments can also beused. Representative examples of black pigments include various carbonblacks (Pigment Black 7) such as channel blacks, furnace blacks, gasblacks, and lamp blacks, and include, for example, carbon blacks soldunder the Regal®, Black Pearls®, Elftex®, Monarch®, Mogul®, and Vulcan®trademarks available from Cabot Corporation (such as Black Pearls® 2000,Black Pearls® 1400, Black Pearls® 1300, Black Pearls® 1100, BlackPearls® 1000, Black Pearls® 900, Black Pearls® 880, Black Pearls® 800,Black Pearls® 700, Black Pearls® 570, Black Pearls® L, Elftex® 8,Monarch® 1400, Monarch® 1300, Monarch® 1100, Monarch® 1000, Monarch®900, Monarch® 880, Monarch® 800, Monarch® 700, Mogul® L, Regal® 660,Regal® 330, Regal® 400, Vulcan® P). Carbon blacks available from othersuppliers can be used. Suitable classes of colored pigments include, forexample, anthraquinones, phthalocyanine blues, phthalocyanine greens,diazos, monoazos, pyranthrones, perylenes, heterocyclic yellows,quinacridones, quinolonoquinolones, and (thio)indigoids. Such pigmentsare commercially available in either powder or press cake form from anumber of sources including, BASF Corporation, Engelhard Corporation,Sun Chemical Corporation, Clariant, and Dianippon Ink and Chemicals(DIC). Examples of other suitable colored pigments are described in theColour Index, 3rd edition (The Society of Dyers and Colourists, 1982).Preferably the pigment is a cyan pigment, such as Pigment Blue 15 orPigment Blue 60, a magenta pigment, such as Pigment Red 122, Pigment Red177, Pigment Red 185, Pigment Red 202, or Pigment Violet 19, a yellowpigment, such as Pigment Yellow 74, Pigment Yellow 128, Pigment Yellow139, Pigment Yellow 155, Pigment Yellow 180, Pigment Yellow 185, PigmentYellow 218, Pigment Yellow 220, or Pigment Yellow 221, an orangepigment, such as Pigment Orange 168, a green pigment, such as PigmentGreen 7 or Pigment Green 36, or black pigment, such as carbon black.

The pigment can have a wide range of BET surface areas, as measured bynitrogen adsorption, depending on the desired properties of the pigment.Preferably, the pigments have a BET surface area between about 10 m²/gand about 1500 m²/g, more preferably between about 20 m²/g and about 600m²/g. If the desired surface area is not readily available for thedesired application, it is also well recognized by those skilled in theart that the pigment may be subjected to conventional size reduction orcomminution techniques, such as ball or jet milling or sonication, toreduce the pigment to a smaller particle size, if desired. Also, thepigment can have a wide variety of primary particle sizes known in theart. For example, the pigment may have a primary particle size ofbetween about 5 nm to about 100 nm, including about 10 nm to about 80 nmand 15 nm to about 50 nm. In addition, the pigment can also have a widerange of dibutylphthalate absorption (DBP) values, which is a measure ofthe structure or branching of the pigment. For example, the pigment maybe a carbon black having a DBP value of from about 25 to 400 mL/100 g,including from about 30 to 200 mL/100 g and from about 50 to 150 mL/100g. Also, the pigment may be an organic colored pigment having an oiladsorption value (as described in ISO 787 T5) of from about 5 to 150mL/100 g, including from about 10 to 100 mL/100 g and from about 20 to80 mL/100 g.

The pigment may also be a pigment that has been oxidized using anoxidizing agent in order to introduce ionic and/or ionizable groups ontothe surface. Pigments prepared in this way have been found to have ahigher degree of oxygen-containing groups on the surface. Oxidizingagents include, but are not limited to, oxygen gas, ozone, NO₂(including mixtures of NO₂ and air), peroxides such as hydrogenperoxide, persulfates, including sodium, potassium, or ammoniumpersulfate, hypohalites such a sodium hypochlorite, halites, halates, orperhalates (such as sodium chlorite, sodium chlorate, or sodiumperchlorate), oxidizing acids such a nitric acid, and transition metalcontaining oxidants, such as permanganate salts, osmium tetroxide,chromium oxides, or ceric ammonium nitrate. Mixtures of oxidants mayalso be used, particularly mixtures of gaseous oxidants such as oxygenand ozone. In addition, pigments prepared using other surfacemodification methods to introduce ionic or ionizable groups onto apigment surface, such as chlorination and sulfonylation, may also beused.

The colorant may also be a modified pigment comprising a pigment havingattached at least one ionic group, ionizable group, or a mixture of anionic group and an ionizable group. The pigment can be any of thosedescribed above. An ionic group is either anionic or cationic and isassociated with a counterion of the opposite charge including inorganicor organic counterions such as Na⁺, K⁺, Li⁺, NH₄ ⁺, NR′₄ ⁺, acetate, NO₃⁻, SO₄ ⁻², R″SO₃ ⁻, R′OSO₃ ⁻, OH⁻, and Cl⁻, where R′, which can be thesame or different, represents hydrogen or an organic group such as asubstituted or unsubstituted aryl and/or alkyl group. An ionizable groupis one that is capable of forming an ionic group in the medium of use.An ionizable groups form anions and cationizable groups form cations.Preferably, the attached group is an organic group. Organic ionic groupsinclude those described in U.S. Pat. No. 5,698,016, the description ofwhich is fully incorporated herein by reference.

Anionic groups are negatively charged ionic groups that may be generatedfrom groups having ionizable substituents that can form anions(anionizable groups), such as acidic substituents. They may also be theanion in the salts of ionizable substituents. Representative examples ofanionic groups include —COO⁻, —SO₃ ⁻, —OSO₃ ⁻, —HPO₃ ⁻, —OPO₃ ⁻², and—PO₃ ⁻². Representative examples of anionizable groups include —COOH,—SO₃H, —PO₃H₂, —R′SH, —R′OH, and —SO₂NHCOR′, where R′ representshydrogen or an organic group such as a substituted or unsubstituted aryland/or alkyl group. Preferably, the attached group comprises acarboxylic acid group, a sulfonic acid group, a sulfate group, or saltsthereof. For example, the attached group may be an organic group such asa benzene carboxylic acid group (a —C₆H₄—COOH group), a benzenedicarboxylic acid group, a benzene tricarboxylic acid group, a benzenesulfonic acid group (a —C₆H₄—SO₃H group), or salts thereof. The attachedorganic group may also be a substituted derivative of any of these.Also, the ionic or ionizable groups may be any of those described inmore detail below relating to the functional group of the polymer.

Cationic groups are positively charged organic ionic groups that may begenerated from ionizable substituents that can form cations(cationizable groups), such as protonated amines. For example, alkyl oraryl amines may be protonated to form ammonium groups —NR′₂H⁺, where R′represent an organic group such as a substituted or unsubstituted aryl,alkyl, aralkyl, or alkaryl group. Cationic groups may also be positivelycharged organic ionic groups. Examples include quaternary ammoniumgroups (—NR′₃ ⁺) and quaternary phosphonium groups (—PR′₃ ⁺). Here, R′represents hydrogen or an organic group such as a substituted orunsubstituted aryl and/or alkyl group. Preferably, the attached groupcomprises an alkyl amine group or a salt thereof or an alkyl ammoniumgroup.

As described above, it is preferred that the colorant is a pigment, and,therefore, the modified colorant is preferably a modified pigment. Themodified pigment comprises the pigment and at least one polymer. In oneembodiment, the modified pigment comprises the pigment coated by thepolymer. In another embodiment, the modified pigment comprises thepigment having attached at least one polymeric group, wherein thepolymeric group comprises the polymer. Thus, the modified pigment may bea pigment having an attached polymer. Preferably, for this embodiment,the polymeric group is directly attached.

For the modified pigments of the present invention comprising either anattached or adsorbed polymer, the polymer comprises at least onefunctional group. As used herein, the term “functional group” relatingto the polymer refers to a pendant group off of the backbone of thepolymer and does not relate to segments or groups that include more thanone repeat unit of the monomer. In a first embodiment of the presentinvention, the functional group of the polymer comprises at least onephosphorus-containing group having at least one P—O or P═O bond, such asat least one phosphonic acid group, at least one phosphinic acid group,at least one phosphinous acid group, at least one phosphite group, atleast one phosphate, diphosphate, triphosphate, or pyrophosphate group,partial esters thereof, or salts thereof. For example, the functionalgroup comprises at least one phosphonic acid group, partial esterthereof, or salt thereof. Preferably the functional group comprises atleast two of these groups, such as at least two phosphonic acid groups,partial esters thereof, or salts thereof. By “partial ester thereof” ismeant that the phosphonic acid group may be a partial phosphonic acidester group having the formula —PO₃RH, or a salt thereof, wherein R isan aryl, alkaryl, aralkyl, or alkyl group. When the functional groupcomprises at least two phosphonic acid groups or salts thereof, eitheror both of the phosphonic acid groups may be a partial phosphonic estergroup. Also, one of the phosphonic acid groups may be a phosphonic acidester having the formula —PO₃R₂ while the other phosphonic acid groupmay be either a partial phosphonic ester group, a phosphonic acid group,or a salt thereof. However, it is preferred that, for this embodiment,at least one of the phosphonic acid groups is either a phosphonic acid,a partial ester thereof, or salts thereof. By “salts thereof” is meantthat the phosphonic acid group may be in a partially or fully ionizedform having a cationic counterion. When the functional group comprisesat least two phosphonic acid groups, either or both of the phosphonicacid groups may be in either a partially or fully ionized form. Thus,preferably the functional group comprises at least two phosphonic acidgroups, wherein either or both may have the formula —PO₃H₂, —PO₃H⁻M⁺(monobasic salt), or —PO₃ ⁻²M⁺ ₂ (dibasic salt), wherein M⁺ is a cationsuch as Na⁺, K⁺, Li⁺, or NR₄ ⁺, wherein R, which can be the same ordifferent, represents hydrogen or an organic group such as a substitutedor unsubstituted aryl and/or alkyl group.

For this embodiment, the functional group may comprise at least onegeminal bisphosphonic acid group, partial esters thereof, or saltsthereof—that is, the functional group may comprise at least twophosphonic acid groups, partial esters thereof, or salts thereof thatare directly bonded to the same carbon atom. Such a group may also bereferred to as a 1,1-diphosphonic acid group, partial ester thereof, orsalt thereof. Thus, for example, the functional group may comprise agroup having the formula —CQ(PO₃H₂)₂, partial esters thereof, or saltsthereof. Q is bonded to the geminal position and may be H, R, OR, SR, orNR₂ wherein R, which can be the same or different, is H, a C1-C18saturated or unsaturated, branched or unbranched alkyl group, a C1-C18saturated or unsaturated, branched or unbranched acyl group, an aralkylgroup, an alkaryl group, or an aryl group. For example, Q may be H, R,OR, SR, or NR₂, wherein R, which can be the same or different, is H, aC1-C6 alkyl group, or an aryl group. Preferably Q is H, OH, or NH₂.Furthermore, the functional group may comprise a group having theformula —(CH₂)_(n)—CQ(PO₃H₂)₂, partial esters thereof, or salts thereof,wherein Q is as described above and n is 0 to 9, such as 1 to 9.Preferably n is 0 to 3, such as 1 to 3, and more preferably, n is either0 or 1. Also, the functional group may comprise a group having theformula —X—(CH₂)_(n)—CQ(PO₃H₂)₂, partial esters thereof, or saltsthereof, wherein Q and n are as described above and X is an arylene,heteroarylene, alkylene, vinylidene, alkarylene, aralkylene, cyclic, orheterocyclic group. For example, X may be an arylene group, such as aphenylene, naphthalene, or biphenylene group, which may be furthersubstituted with any group, such as one or more alkyl groups or arylgroups. When X is an alkylene group, examples include, but are notlimited to, substituted or unsubstituted alkylene groups, which may bebranched or unbranched and can be substituted with one or more groups,such as aromatic groups. Examples include, but are not limited to,C₁-C₁₂ groups like methylene, ethylene, propylene, or butylene, groups.

X may be further substituted with one or more additional functionalgroups. Examples of additional functional groups include, but are notlimited to, R′, OR′, COR′, COOR′, OCOR′, carboxylates, halogens, CN,NR′₂, SO₃H, sulfonates, sulfates, NR′(COR′), CONR′₂, imides, NO₂,phosphates, phosphonates, N═NR′, SOR′, NR′SO₂R′, and SO₂NR₂′, wherein R′which can be the same or different, is independently hydrogen, branchedor unbranched C₁-C₂₀ substituted or unsubstituted, saturated orunsaturated hydrocarbons, e.g., alkyl, alkenyl, alkynyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, substitutedor unsubstituted alkaryl, or substituted or unsubstituted aralkyl.

In addition, the functional group may be comprise a group having theformula -Sp-(CH₂)_(n)—CQ(PO₃H₂)₂, partial esters thereof, or saltthereof, wherein Q and n are as described above. Sp is a spacer group,which, as used herein, is a link between two groups. Sp can be a bond ora chemical group. Examples of chemical groups include, but are notlimited to, —CO₂—, —O₂C—, —CO—, —OSO₂—, —SO₃—, —SO₂—, —SO₂C₂H₄O—,—SO₂C₂H₄S—, —SO₂C₂H₄NR″—, —O—, —S—, —NR″—, —NR″CO—, —CONR″—, —NR″CO₂—,—O₂CNR″—, —NR″CONR″—, —N(COR″)CO—, —CON(COR″)—, —NR″COCH(CH₂CO₂R″)— andcyclic imides therefrom, —NR″COCH₂CH(CO₂R″)— and cyclic imidestherefrom, —CH(CH₂CO₂R″)CONR″— and cyclic imides therefrom,—CH(CO₂R″)CH₂CONR″ and cyclic imides therefrom, (including phthalimideand maleimides of these), sulfonamide groups (including —SO₂NR″— and—NR″SO₂— groups), arylene groups, alkylene groups and the like. R″,which can be the same or different, represents hydrogen or an organicgroup such as a substituted or unsubstituted aryl or alkyl group.Preferably, Sp is —CO₂—, —O₂C—, —O—, —NR″—, —NR″CO— or —CONR″—,—SO₂NR″—, —SO₂CH₂CH₂NR″—, —SO₂CH₂CH₂O—, or —SO₂CH₂CH₂S— wherein R″ is Hor a C1-C6 alkyl group.

In addition, the functional group may comprise at least one group havingthe formula —N—[(CH₂)_(m)(PO₃H₂)]₂, partial esters thereof, or saltsthereof, wherein m, which can be the same or different, is 1 to 9.Preferably m is 1 to 3 and more preferably is 1 or 2. For example, thefunctional group may comprise at least one group having the formula—(CH₂)_(n)—N—[(CH₂)_(m)(PO₃H₂)]₂, partial esters thereof, or saltsthereof, wherein n is 0 to 9, such as 1 to 9, and is preferably 0 to 3,such as 1 to 3, and m is as defined above. Also, the functional groupmay comprise at least one group having the formula—X—(CH₂)_(n)—N—[(CH₂)_(m)(PO₃H₂)]₂, partial esters thereof, or saltsthereof, wherein X, m, and n are as described above. Also, thefunctional group may comprise at least one group having the formula-Sp-(CH₂)_(n)—N—[(CH₂)_(m)(PO₃H₂)]₂, partial esters thereof, or saltsthereof, wherein m, n, and Sp are as described above.

In addition, the functional group may comprise at least one group havingthe formula —CR═C(PO₃H₂)₂, partial esters thereof, or salts thereof. Rcan be H, a C1-C18 saturated or unsaturated, branched or unbranchedalkyl group, a C1-C18 saturated or unsaturated, branched or unbranchedacyl group, an aralkyl group, an alkaryl group, or an aryl group.Preferably, R is H, a C1-C6 alkyl group, or an aryl group.

For this embodiment, the functional group may comprise more than twophosphonic acid groups, partial esters thereof, or salts thereof andmay, for example, comprise more than one type of group (such as two ormore) in which each type of group comprises at least two phosphonic acidgroups, partial esters thereof, or salts thereof. For example, thefunctional group may comprise a group having the formula—X—[CQ(PO₃H₂)₂]_(p), partial esters thereof, or salt thereof. X and Qare as described above, and preferably X is an arylene, heteroarylene,alkylene, alkarylene, or aralkylene group. In this formula, p is 1 to 4and is preferably 2.

In addition, the functional group may comprise at least one vicinalbisphosphonic acid group, partial ester thereof, or salts thereof,meaning that these groups are adjacent to each other. Thus, thefunctional group may comprise two phosphonic acid groups, partial estersthereof, or salts thereof bonded to adjacent or neighboring carbonatoms. Such groups are also sometimes referred to as 1,2-diphosphonicacid groups, partial esters thereof, or salts thereof. The groupcomprising the two phosphonic acid groups, partial esters thereof, orsalts thereof may be an aromatic group or an alkyl group, and thereforethe vicinal bisphosphonic acid group may be a vicinal alkyl or a vicinalaryl diphosphonic acid group, partial ester thereof, or salts thereof.For example, the functional group may be a group having the formula—C₆H₃—(PO₃H₂)₂, partial esters thereof, or salts thereof, wherein theacid, ester, or salt groups are in positions ortho to each other.

In a second embodiment of the present invention, the functional groupcomprises at least one hydroxamic acid group or salt thereof. Thus, thefunctional group may comprise at least one group having the formula—N(OH)—CO— or a salt thereof. Such groups include, for example, amide orimide groups in which the amide or imide nitrogen is substituted with anOH group, and tautomers thereof. The hydroxamic acid group may beacyclic, in which the N—C bond is part of a non-cyclic group, or cyclic,in which the N—C bond is part of a cyclic group. Preferably, the cyclichydroxamic acid group is a heterocyclic group, and more preferably aheteroaryl group, such as a hydroxy pyridonyl group (which may also bereferred to as a hydroxy pyridinyl N-oxide group) or a hydroxyquinolonyl group (which may also be referred to as a hydroxy quinolinylN-oxide group). Specific examples include a 1-hydroxy-2-pyridonyl group,a 1-hydroxy-2-quinolonyl group, or salts thereof. One skilled in the artwould recognize that isomers and tautomers of these can also be used. Inaddition, the functional group may further comprise additionalfunctional groups, including those described above, such as those for X.

In a third embodiment of the present invention, the functional groupcomprises at least one heteroaryl group having at least one OH group, orsalts thereof. Preferably the heteroaryl group is a nitrogen-containingheteroaryl group, such as a pyridinyl group or a quinolinyl group, andthe functional group is a hydroxy pyridinyl group or a hydroxyquinolinyl group. The hydroxy group is preferably at a position on theheteroaryl group such that it is geometrically close to the heteroatom,such as ortho to the heteroatom. Such a group may be in the salt form.For example, the functional group may comprise a 2-hydroxy pyridinylgroup or a 2-hydroxy-quinolinyl group, as well as an8-hydroxy-quinolinyl group or salts thereof. Other isomers or tautomerswill also be known to one skilled in the art. Preferably the functionalgroup comprises an 8-hydroxy-quinolinyl group. In addition, thefunctional group may further comprise additional functional groups,including those described above for X. For example, electron withdrawinggroups, such as chloro or nitro groups, may be included in order tolower the pKa of the OH group.

For this embodiment, the functional group may also comprise at least oneheteroaryl group having at least two OH groups. When there are two OHgroups, preferably the OH groups are in positions ortho to each other onthe heteroaryl group. When there are more than two OH groups, it ispreferred that at least two of the OH groups are in positions ortho toeach other on the heteroaryl group. For example, the functional groupmay be a dihydroxy-pyridinyl group, such as a 2,3-dihydroxy-pyridinylgroup (which can also be referred to as a 3-hydroxy-2-pyridonyl group),a 3,4-dihydroxy-pyridinyl group (which can also be referred to as a3-hydroxy-4-pyridonyl group), a 2,3-dihydroxy-quinolinyl group (whichcan also be referred to as 3-hydroxy-2-quinolonyl group), or a3,4-dihydroxy-quinolinyl group (which can also be referred to as a3-hydroxy-4 quinolonyl group). Other isomers and tautomers will also beknown to one skilled in the art.

In a fourth embodiment of the present invention, the functional groupcomprises at least one phosphonic acid group, partial ester thereof, orsalts thereof and at least one second ionic or ionizable group. Thesecond group is not a phosphonic acid group or salt thereof. Preferably,the second ionic or ionizable group is a carboxylic acid group, asulfonic acid group, or a salt thereof. Preferably the basic group is aLewis base, such as an OH group (a hydroxyl group) or an amino group.Preferably these two groups are geminal to each other, by which ismeant, are directly bonded to the same carbon atom. Thus, for example,when the second ionic or ionizable group is a carboxylic acid group orsalt thereof, the functional group may comprise a group having theformula —CQ(PO₃H₂)(CO₂H) or salts thereof. Q, which is bonded to thegeminal position, may be any of those described above. Preferably, Q isH. In addition, the functional group may comprise a group having theformula —(CH₂)_(n)—CQ(PO₃H₂)(CO₂H) or salts thereof, wherein n is 0 to 9and is preferably 0 to 3. Furthermore, the functional group may comprisea group having the formula —X—(CH₂)_(n)—CQ(PO₃H₂)(CO₂H) or salt thereof,wherein X is as described above. For example, X may be an arylene group.Also, the functional group may comprise a group having the formula-Sp-(CH₂)_(n)—CQ(PO₃H₂)(CO₂H) or salt thereof, wherein Sp, which is aspacer group, are as described above.

As a further example for this embodiment, the functional group maycomprise at least one phosphonic acid group, a partial ester thereof, orsalts thereof and at least one hydroxy group or salt thereof, such as agroup having the formula —X—(PO₃H₂)(OH) or salts thereof, wherein X isas described above. Preferably, X is an arylene group and, for thispreferred formula, the phosphonic acid group and hydroxy group are inpositions ortho to each other. When these groups are geminal, theorganic group may comprise at least one group having the formula—CR(PO₃H₂)(OH) or salts thereof, wherein R is H or a C1-C6 alkyl group.Preferably, R is H. Also, the functional group may comprise at least onegroup having the formula —(CH₂)_(n)—CR(PO₃H₂)(OH) or salts thereof,wherein n is 0 to 9 and is preferably 0 to 3. Furthermore, thefunctional group may comprise a group having the formulas—X—(CH₂)_(n)—CR(PO₃H₂)(OH) or salts thereof or-Sp-(CH₂)_(n)—CR(PO₃H₂)(OH) or salts thereof, wherein Sp are asdescribed above.

In a fifth embodiment of the present invention, the functional groupcomprises a heteroaryl group having at least one carboxylic acid groupor salt thereof. While the heteroaryl group may be any of those known inthe art, preferably the heteroaryl group is a nitrogen containingheteroaryl group, such as a pyridinyl group, a pyrimidinyl group, apyrrolyl group, a quinolinyl group, or a pyrazinyl group. Preferably thefunctional group comprises two carboxylic acid groups or salts thereof.These acid groups may be anywhere on the heteroaryl ring but arepreferably either ortho or meta to each other. Furthermore, when theheteroaryl group contains at least one nitrogen atom, it is preferredthat the two acid groups are both adjacent to (that is, ortho to) thenitrogen atom. Thus, for example, the heteroaryl group may be a2,6-pyridinyl-dicarboxylic acid group.

In a sixth embodiment of the present invention, the functional comprisesan aryl group having at least one nitroso group and at least one OHgroup, or a salt thereof. The two groups may be located anywhere on thearyl group. Preferably, the aryl group is a phenyl group and the nitrosoand OH groups are in positions ortho to each other. The aryl group mayfurther comprise other substituents, such as alkyl groups, halogengroups, ether groups and the like, including electron withdrawinggroups, such as chloro and nitro groups, capable of lowering the pKa ofthe organic group, regardless of which tautomeric form it is in. Forexample, the functional group can be a nitrosophenolic group, such as agroup having the formula —C₆H₃ (OH)(NO) or, preferably a group havingthe formula —C₆H₂Z(OH)(NO), wherein Z is an electron withdrawing groupsuch as chloro or nitro.

In a seventh embodiment of the present invention, the functional groupcomprises an azoarene group. For example, the functional group maycomprise a group having the formula Ar¹—N═N—Ar², wherein Ar¹ and Ar²,which can be the same or different, are an arylene group, such as aphenylene or a naphthylene group, or an aryl group, such as a phenylgroup or a naphthyl group, and at least one of Ar¹ or Ar² is an arylenegroup. For this embodiment, the azoarene group has at least one andpreferably at least two OH groups, at least one and preferably at leasttwo NH₂ groups, or at least one OH group and at least one NH₂ group.Thus, for example, the azoarene group may have the formula—(HO)Ar¹—N═N—Ar²(OH) (a bis-hydroxy azoarene group),—(H₂N)Ar¹—N═N—Ar²(NH₂) (a bis-amino azoarene group), or—(HO)Ar¹—N═N—Ar²(NH₂) or —(H₂N)Ar¹—N═N—Ar²(OH) (an amino-hydroxyazoarene group). Other combinations may also be possible. Preferably,the OH and/or NH₂ groups are located at positions ortho to the azo group(the N═N group). For example, the functional group may be a group havingthe structure —(HO)C₆H₃—N═N—C₆H₄(OH). Also, electron withdrawing groups,such as chloro or nitro groups, may be included on the aryl and/orarylene groups. Thus, preferably, the organic group is a group havingthe structure —(HO)C₆H₃—N═N—C₆H₃Z(OH), wherein Z is an electronwithdrawing group such as chloro or nitro.

In an eighth embodiment of the present invention, the functional groupcomprises an aryl or alkyl polyacid group comprising at least twocarboxylic acid groups, preferably at least three carboxylic acidgroups. For example, the functional group may be an alkyl poly-acidgroup having at least two acid groups, at least three, four, or moreacid groups, such as at least two carboxylic acid groups, at least threeor more carboxylic groups, as well as other types of acid groups inaddition or in the alternative. For example, the functional group maycomprise two carboxylic acid groups and at least one ether or aminogroup. Specific examples of functional groups include—CH(CO₂H)CH₂OC₂H₄CO₂H, —CH(CH₂CO₂H)OC₂H₄CO₂H,—CH(CH₂OC₂H₄CO₂H)(OC₂H₄CO₂H), and —CH(CO₂H)N(CH₂CO₂H)₂. The functionalgroup may also comprise an aryl polyacid group. This group comprises atleast two carboxylic acid groups. Preferably, the carboxylic acid groupsare vicinal to each other. Thus, the aryl polyacid group can besubstituted with at least one group that comprises two adjacentcarboxylic acid groups (i.e., carboxylic acid groups bonded to adjacentor neighboring carbon atoms), sometimes also referred to as a vicinaldicarboxylic acid or a 1,2-dicarboxylic acid. Thus, the aryl polyacidgroup may comprise a group having three or more carboxylic acid groups,wherein at least two of the carboxylic acid groups are adjacent to eachother, forming a vicinal dicarboxylic acid group. For example, thearomatic amine may comprise a 1,2,3- or 1,2,4-tricarboxylic acid group,such as a —C₆H₂—(COOH)₃ group, or may comprise a 1,2,3,4- or1,2,4,5-tetra carboxylic acid group, such as a —C₆H—(COOH)₄ group. Othersubstitution patterns are also possible and will be known to one skilledin the art.

For each of these embodiments, the amount of functional groups can bevaried, depending on the desired use of the modified colorant and thetype of attached group. Also, the amount of polymeric group, comprisingthe polymer, may also be varied. For example, the total amount ofpolymer group may be from about 1-80% by weight of the modifiedcolorant, preferably 5-60%, and more preferably 10-40% by weightpolymer. The amount of attached polymer can be determined using anymethod known in the art. Additional attached organic groups, whichdiffer from those described for the various embodiments of the presentinvention, may also be present and are described in more detail below.

The modified colorant and, in particular, the modified pigment may beeither in a solid form, such as a powder or a paste, or in a dispersionform. For example, the modified pigment may be produced in the form of adispersion, and isolated from the dispersion in the form of a solid,such as by spray drying. Alternatively, a solid form of the modifiedpigment may be produced directly. Preferably the modified pigment is inthe form of a dispersion. The modified pigment dispersion may bepurified by washing, such as by filtration, centrifugation, or acombination of the two methods, to remove unreacted raw materials,byproduct salts and other reaction impurities. The products may also beisolated, for example, by evaporation or it may be recovered byfiltration and drying using known techniques to those skilled in theart.

The modified pigment may also be dispersed into a liquid medium, and theresulting dispersions may be purified or classified to remove impuritiesand other undesirable free species that can co-exist in the dispersionas a result of the manufacturing process. For example, the dispersioncan be purified to remove any undesired free species, such as unreactedtreating agent using known techniques such asultrafiltration/diafiltration, reverse osmosis, or ion exchange.Preferably, the large particle concentration of the dispersion is alsoreduced in order to improve the overall dispersion stability. Thus, forexample, particles having a size greater than 500 nm can be removedusing techniques such as centrifugation.

It is preferred that the functional group of the polymer be a group thathas a high calcium index value. As used herein, the term “calcium indexvalue” refers to a measure of the ability of a functional group tocoordinate or bind calcium ions in solution. The higher the calciumindex value, the more strongly or effectively the group can coordinatecalcium ions. Such a value can be determined using any method known inthe art. For example, the calcium index value may be measured using amethod in which the amount of calcium coordinated by a compound in astandard solution containing soluble calcium ions and a color indicatoris measured using UV-Vis spectroscopy. In addition, for compounds havinga strong color, the calcium index value may be measured using an NMRmethod. Also, for some compounds, values measured using known literaturetechniques can be used. Details relating to specific methods aredescribed below.

As used herein, the term “high” in reference to the calcium index valuemeans that the value is greater than that of a reference material. Forthe purposes of the present invention, the reference is phenylphosphonicacid. Alkyl phosphonic acids, such as ethyl or isopropyl phosphonicacid, would be expected to have a calcium index value slightly higherthan that of phenylphosphonic acid. Therefore, preferably the referencehas a calcium index value greater than these. More preferably, thereference is 1,2,3-benzene tricarboxylic acid. Thus, the functionalgroup of the polymer attached to the pigment has a calcium index valuethat is greater than the calcium index value of phenyl phosphonic acidand more preferably has a calcium index value greater than or equal tothat of 1,2,3-benzene tricarboxylic acid. Preferably, the functionalgroup has a calcium index value greater than or equal to 2.8, morepreferably greater than 3.0, and most preferably greater than 3.2,determined using UV-Vis spectroscopy, as described in more detail below.Surprisingly it has been found that modified colorants and, inparticular, modified pigments comprising pigments having attachedpolymeric groups described herein, particularly those comprisingfunctional groups having a calcium index value greater than that ofphenylphosphonic acid and more preferably greater than or equal to thatof 1,2,3-benzene tricarboxylic acid, have improved properties,especially when used in an inkjet ink composition, compared to otherattached groups, particularly those that have a calcium index value thatis less than these reference compounds. For modified pigments coated bythe polymer, the functional group preferably has a calcium index valuegreater than or equal to that of 1,2,3-benzene tricarboxylic acid.

The polymers having the functional groups described above can be ahomopolymer, copolymer, terpolymer, and/or a polymer containing anynumber of different repeating units. Further, the polymer can be arandom polymer, branched polymer, alternating polymer, graft polymer,block polymer, star-like polymer, and/or comb-like polymer. The type ofpolymer can be varied depending on the intended application. Forexample, the polymeric group comprises a polymer comprising acid groupsand having an acid number of less than 200, such as less than 150, orless than 100, or less than 50. Acid numbers can be determined using anymethod known in the art, including titration with a strong base such asKOH. Specific examples include acid numbers between 100 and 200, between50 and 100, and between 0 and 50. Also, the polymer may have a Tg lessthan 100, such as between 50 and 100, and preferably less than 50.Furthermore, the polymer may have a molecular weight (Mw) of betweenabout 500-100,000 such as between about 1000 and 50,000 and betweenabout 2,000 and 25,000. The polydispersity of the polymer of thepolymeric group is generally less than 3, such as less than 2.5, andless than 2. Alternatively, the molecular weight distribution may bepolymodal, such as bimodal. As noted above, the polymeric group attachedto the modified pigment of the present invention may comprise any ofthese polymers or a combination of polymers.

The polymer having the functional groups described above may be preparedusing any method known in the art. For example, the polymer can beprepared using a variety of different polymerization techniques thatinclude the use of at least one monomer comprising the functional group.Preferably the polymer is prepared by the polymerization of a radicallypolymerizable monomer comprising at least one of the groups describedabove. For example, the monomer may be vinylphosphonic acid, partialesters thereof, or salts thereof or vinylidene diphosphonic acid,partial esters thereof, or salts thereof. Preferably, the salts arethose that enable the monomer to be at least partially soluble in anorganic solvent. For example, the monomer may be a tetraalkyl ammoniumsalt, such as a tetraethyl or tetrabutyl ammonium salt. Mixed salts andpartial salts, such as combinations of the acid form with sodium and/oralkyl ammonium salts, can also be used. The monomers may also be anacrylamide, a methacrylamide, an acrylate ester, a methacrylate ester, avinyl ester, a vinyl ether, or a styrene monomer that comprises at leastone of the groups described above. Specific examples include acrylamides(and methacrylamides) prepared by the reaction of acryloyl chloride oracrylic acid, or esters thereof, such as methyl acrylate (ormethacryloyl chloride and methacrylic acid or esters thereof), aminecompounds comprising the functional groups described above, such asalkylamines comprising at least one bisphosphonate group, and styrenederivatives such as [2-(4-vinylphenyl)ethane-1,1-diyl]bisphosphonicacid, [hydroxy(4-vinylphenyl)methylene]bisphosphonic acid, and{1-hydroxy-4-[4-vinylbenzoyl)amino]butane-1,1-diyl}bisphosphonic acid.Specific acrylamides and methacrylamides include4-methacrylamido-(1,2-benzenedicarboxylic acid),4-acrylamido-(1,2-benzenedicarboxylic acid),5-methacrylamido-(1,2,3-benzenetricarboxylic acid),5-acrylamido-(1,2,3-benzenetricarboxylic acid),5-methacrylamido-(1,2,4-benzenetricarboxylic acid),5-acrylamido-(1,2,4-benzenetricarboxylic acid),5-methacrylamido-2-hydroxypyridine-N-oxide,6-methacrylamido-2-hydroxyquinoline-N-oxide, and4-methacrylamido-1-hydroxybutane-1,1-diphosphonic acid.

The polymer can also be prepared by the polymerization of at least oneof the monomers described above and one or more additional monomers notcomprising one of the groups described above. Such monomers may providethe polymer with additional desirable properties, particularly useful inan inkjet ink composition. Examples include, but are not limited to,acrylic and methacrylic acid, acrylate esters, methacrylate esters,acrylamides and methacrylamides, acrylonitriles, cyanoacrylate esters,maleate and fumarate diesters, vinyl pyridines, vinyl N-alkylpyrroles,vinyl acetate, vinyl oxazoles, vinyl thiazoles, vinyl pyrimidines, vinylimidazoles, vinyl ketones, vinyl ethers, and styrenes. Vinyl ethersinclude those that can be prepared by cationic polymerization, such asthose having the general structure CH₂═CH(OR), wherein R is an alkyl,aralkyl, alkaryl, or aryl group or is a group comprising one or morealkylene oxide groups. Vinyl ketones include those in which the β-carbonatom of the alkyl group does not bear a hydrogen atom, such as vinylketones in which both β-carbons bear a C1-C4 alkyl group, halogen, etc.or a vinyl phenyl ketone in which the phenyl group may be substitutedwith from 1 to 5 C1-C6 alkyl groups and/or halogen atoms. Styrenesinclude those in which the vinyl group is substituted with a C1-C6 alkylgroup, such as at the α-carbon atom, and/or those in which the phenylgroup is substituted with from 1 to 5 substituents including a C1-C6alkyl, alkenyl (including vinyl), or alkynyl (including acetylenyl)group, a phenyl group, a haloalkyl group, and functional groups such asC1-C6 alkoxy, halogen, nitro, carboxy, sulfonate, C1-C6 alkoxycarbonyl,hydroxy (including those protected with a C1-C6 acyl group), and cyanogroups. Specific examples include methyl acrylate (MA), methylmethacrylate (MMA), ethyl acrylate (EA), ethyl methacrylate (EMA), butylacrylate (BA), 2-ethylhexyl acrylate (EHA), acrylonitrile (AN),methacrylonitrile, styrene, and derivatives thereof.

The polymer can be prepared by the cationic or anionic polymerization ofone or more polymerizable monomers. For example, polyvinyl ethers can beprepared by cationic polymerization of monomers, such as those havingthe general structure CH₂═CH(OR), wherein R is an alkyl, aralkyl,alkaryl, or aryl group or is a group comprising one or more alkyleneoxide groups. Other cationically or anionically polymerizable monomerscan also be included.

The polymer can also be prepared by polycondensation techniques. Forexample, the polymer may be a polyester or a polyurethane having afunctional group described above. For polyurethanes, examples ofsuitable methods include a solution method which comprises preparing anisocyanate-terminated prepolymer in a low boiling solvent (such asacetone) unreactive with an isocyanate group, introducing a hydrophilicgroup such as diamine or polyol therein, effecting phase change bydiluting with water, and distilling off a solvent to obtain apolyurethane dispersion. Another suitable method comprises preparing anisocyanate group-terminated prepolymer having a hydrophilic groupintroduced, dispersing in water, and extending a chain with an amine.

Particularly, a polyurethane may be prepared by the prepolymer method,and a polyhydroxy compound having a low molecular weight may be used atthat time. Examples of the polyhydroxy compound having a low molecularweight include the above illustrated starting materials of the polyesterdiol, such as glycol and alkylene oxide-low mol adduct, a trihydricalcohol such as glycerin, trimethylolethane or trimethylolpropane, itsalkylene oxide-low mol adduct, and the like.

For water dispersible polyurethanes, it is generally known to use amethod which comprises effecting phase change of a urethane polymerprepared in an organic solvent phase and emulsifying to further extend achain in an aqueous phase. It is usual to use polyamines such as diamineas a chain extender at that time. For example, the urethane prepolymeris subjected to neutralization of an acid group derived fromdimethylolalkanoic acid and chain extension with water or di- ortriamine after or while neutralizing. Examples of the polyamines used asa chain extender in the amine extension include generally diamine ortriamine. Their particular examples include hexamethylenediamine,isophoronediamine, hydrazine, piperazine and the like.

The polymers comprising the functional groups described above may alsobe prepared by reacting a reagent that comprises the desired functionalgroup and a reactive group of the polymer. For example, the reagent maybe an amine reagent comprising the desired functional group and thepolymer may comprise a carboxylic acid or ester group as the reactivegroup. Other reactive groups may include acid anhydrides, acid halides,activated esters such as nitrophenyl esters or the reaction product of acarboxylic acid and N-hydroxysuccinimide, isocyanates, epoxides,thioepoxides, and aziridines. This reaction can be driven by heating orthermal dehydration. Alternatively, coupling agents such ascarbodiimides may be used, for example, to react a carboxylic acid withan amine. Mixed anhydrides may also be used. These can react in order toform a polymer having the desired functional group. In addition, thepolymer may be prepared by reacting a reagent having the functionalgroup, a polymer having at least one reactive group, and at least onelinking reagent. The linking reagent is one that is capable of reactingwith both the reagent and the reactive group. For example, the reagentmay be an amine reagent and the reactive group may comprise an aminogroup. In this case, the linking agent could be a dicarboxylic acidcompound, an anhydride, a bis-epoxide, or a polyfunctional aziridine.Furthermore, the polymer may be prepared by direct conversion ofcarboxylic acids or derivatives thereof (such as halides, esters,amides, or nitriles), such as by phosphonylation. In these ways, avariety of polymers may be converted to polymers described herein byreacting or attached the specified functional group to the polymerbackbone.

Modified pigments having attached polymeric groups of the presentinvention may be prepared using any method known in the art. Preferablythe polymeric group is directly attached. Such modified pigments may beprepared using any method known to those skilled in the art such thatorganic chemical groups are attached to the pigment. For example, thepolymer modified pigments may be prepared by the reaction of afunctional group of a polymer with a functional group of a pigment (asshown in, for example, U.S. Pat. No. 6,723,783 or European Patent No. 0272 127), including the reaction of an end or terminal functionalpolymer and a pigment. Other methods for preparing the modified pigmentsby reacting a pigment having available functional groups with a polymercomprising the functional group include those described in, for example,U.S. Pat. No. 6,723,783, which is incorporated in its entirety byreference herein. Such functional pigments may be prepared using themethods described in U.S. Pat. Nos. 5,554,739, 5,707,432, 5,837,045,5,851,280, 5,885,335, 5,895,522, 5,900,029, 5,922,118, and 6,042,643,and PCT Publication WO 99/23174, the descriptions of which are fullyincorporated herein by reference. Such methods provide for a more stableattachment of the groups onto the pigment compared to dispersant typemethods, which use, for example, polymers and/or surfactants.Alternatively, these modified pigments can be prepared by the reactionof an amine-containing functional group of a polymer with a diazotizingagent which is then further reacted with a pigment (as shown in, forexample, U.S. Pat. No. 6,478,863), which may also utilize the methodsdescribed in the references above. In addition modified carbon blackscontaining attached polymeric groups may also be prepared from pigmentsprepared by the methods described in U.S. Pat. Nos. 6,831,194 and6,660,075, U.S. Patent Publication Nos. 2003-0101901 and 2001-0036994,Canadian Patent No. 2,351,162, European Patent No. 1 394 221, and PCTPublication No. WO 04/63289, as well as in N. Tsubokawa, Polym. Sci.,17, 417, 1992, each of which is also incorporated in their entirety byreference herein.

Furthermore, the polymer modified pigments may also be prepared bypolymerization of monomers from a pigment. For example, the polymermodified pigments may be prepared by radical polymerization, controlledpolymerization methods, such as atom transfer radical polymerization(ATRP), stable free radical (SFR) polymerization, and reversibleaddition-fragmentation chain transfer polymerization (RAFT), ionicpolymerizations (anionic or cationic) such as group transferpolymerization (GTP), and condensation polymerization. Also, the polymermodified pigments may be prepared using the methods described in, forexample, U.S. Pat. Nos. 6,372,820; 6,350,519; 6,551,393; or 6,368,239 orin International Patent Publication Nos. 2006/086599 and 2006/086660,which are incorporated in their entirety by reference herein. Formodified pigments comprising the pigment coated by the polymer, thesemodified pigments can be prepared using any method known in the art,such as those described in U.S. Pat. Nos. 5,085,698, 5,998,501,6,074,467, 6,852,777, and 7,074,843, and International PatentPublication Nos. WO 2004/111,140, WO 2005/061087, and WO 2006/064193,each incorporated in their entirety by reference herein.

The modified colorants of the present invention, particularly themodified pigments comprising a pigment having attached at least onepolymeric group, may further comprise a second organic group, which isdifferent from the polymeric groups described above. These include, forexample, the groups described in U.S. Pat. No. 5,630,868, which isincorporated in its entirety by reference herein. For example, themodified pigment may further comprise a second attached organic groupthat may comprise at least one ionic group, at least one ionizablegroup, or a mixture thereof. Preferably the ionic or ionizable group isan anionic or anionizable group. Any of the ionic or ionizable groups,particularly the anionic or anionizable groups, described aboveregarding the pigment of the modified pigment of the present inventionmay be the second organic group. Furthermore, the second organic groupmay be a polymeric group comprising a polymer. Any of the polymericgroups described above can also be used as the second attached organicgroup.

The modified colorants of the present invention may be used in a varietyof applications, including, for example, plastic compositions, aqueousor non-aqueous inks, aqueous or non-aqueous coatings, rubbercompositions, paper compositions and textile compositions. Inparticular, these pigments may be used in aqueous compositions,including, for example, automotive and industrial coatings, paints,toners, adhesives, latexes, and inks. The pigments have been found to bemost useful in ink compositions, especially inkjet inks.

Thus, the present invention further relates to an inkjet ink compositioncomprising a vehicle, a colorant, and a polymer. The polymer can be anyof those described above. Thus, for example, the inkjet ink compositionof the present invention can comprise a polymer having any of thefunctional groups described above and is either a separate additive inthe composition or may be associated with the colorant, such as amodified colorant of the present invention having the polymer eitherattached or adsorbed thereto. Preferably the colorant is a pigment. Thevehicle can be either an aqueous or non-aqueous liquid vehicle, but ispreferably a vehicle that contains water. Thus, the vehicle ispreferably an aqueous vehicle, and the inkjet ink composition is anaqueous inkjet ink composition. More preferably the vehicle containsgreater than 50% water and includes, for example, water or mixtures ofwater with water miscible solvents such as alcohols.

The colorant can be any of the colorants described above and ispreferably a modified pigment, as discussed above. The colorant ispresent in the inkjet ink composition in an amount effective to providethe desired image quality (for example, optical density) withoutdetrimentally affecting the performance of the inkjet ink. Typically,the colorant is present in an amount ranging from about 0.1% to about30% based on the weight of the ink. More or less colorant may be useddepending on a variety of factors. For example, for the inkjet inkcomposition comprising the modified pigments of the present invention,the amount of pigment may vary depending on the amount of attachedpolymeric group. Also, the amount of polymer will vary depending on thetype of colorant. Typically the ratio of polymer to pigment is betweenabout 4:1 and 1:100, including between about 1:1 and about 1:5.

It is also within the bounds of the present invention to use a mixtureof colorants, including, for example, a mixture of the various modifiedpigments described herein, or mixtures of these modified pigments andunmodified pigments, such as oxidized pigments, includingself-dispersible oxidized pigments prepared using peroxide, ozone,persulfate, and hypohalites (some of which are commercially availablefrom Rohm and Haas or Orient), other modified pigments, or both. Also,mixtures of modified colorants wherein one colorant comprises a dye andone colorant comprises a pigment may also be used.

For example, the inkjet ink composition of the present invention maycomprises a liquid vehicle, a first modified pigment, which is amodified pigment of the present invention as described above, and asecond modified pigment comprising a second pigment having attached atleast one second organic group, which is different from the organicgroup of the first modified pigment. The pigment and the second pigmentmay be the same or different, depending, for example, if the blends ofpigments are to create a specific target color or if the blend ofpigments is to provide the same color using different types of modifiedpigments. The second organic group can be a group comprising at leastone ionic group, at least one ionizable group, or a mixture thereof. Anyof the ionic or ionizable groups described above relating to a secondattached organic group of the modified pigment can be used here.

Also, the inkjet ink composition of the present invention may comprise aliquid vehicle, a first modified pigment, which is a modified pigment ofthe present invention as described above, and a second modified pigmentcomprising a second pigment having at least one attached or adsorbedpolymer. Any of the polymers described above relating to the modifiedpigment of the present invention may also be used here. For example, thesecond modified pigment may be a polymer coated pigment, such as apolymer encapsulated pigment, comprising a pigment and at least oneadsorbed polymer. Also, the second modified pigment may comprise apigment having at least one attached polymeric group, wherein thepolymeric group comprises the polymer.

The inkjet ink composition of the present invention can be formed with aminimum of additional components (additives and/or cosolvents) andprocessing steps. However, suitable additives may be incorporated inorder to impart a number of desired properties while maintaining thestability of the compositions. For example, surfactants and/ordispersants, humectants, drying accelerators, penetrants, biocides,binders, and pH control agents, as well as other additives known in theart, may be added. The amount of a particular additive will varydepending on a variety of factors but generally ranges between 0% and40%.

Dispersing agents (surfactants and/or dispersants) may be added tofurther enhance the colloidal stability of the composition or to changethe interaction of the ink with either the printing substrate, such asprinting paper, or with the ink printhead. Various anionic, cationic andnonionic dispersing agents can be used in conjunction with the inkcomposition of the present invention, and these may be in solid form oras a water solution.

Representative examples of anionic dispersants or surfactants include,but are not limited to, higher fatty acid salts, higheralkyldicarboxylates, sulfuric acid ester salts of higher alcohols,higher alkyl-sulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, naphthalene sulfonates (Na, K, Li, Ca, etc.), formalinpolycondensates, condensates between higher fatty acids and amino acids,dialkylsulfosuccinic acid ester salts, alkyl sulfosuccinates,naphthenates, alkylether carboxylates, acylated peptides, α-olefinsulfonates, N-acrylmethyl taurine, alkylether sulfonates, secondaryhigher alcohol ethoxysulfates, polyoxyethylene alkylphenylethersulfates, monoglycylsulfates, alkylether phosphates and alkylphosphates, alkyl phosphonates and bisphosphonates, includedhydroxylated or aminated derivatives. For example, polymers andcopolymers of styrene sulfonate salts, unsubstituted and substitutednaphthalene sulfonate salts (e.g. alkyl or alkoxy substitutednaphthalene derivatives), aldehyde derivatives (such as unsubstitutedalkyl aldehyde derivatives including formaldehyde, acetaldehyde,propylaldehyde, and the like), maleic acid salts, and mixtures thereofmay be used as the anionic dispersing aids. Salts include, for example,Na⁺, Li⁺, K⁺, Cs⁺, Rb⁺, and substituted and unsubstituted ammoniumcations. Specific examples include, but are not limited to, commercialproducts such as Versa® 4, Versa® 7, and Versa® 77 (National Starch andChemical Co.); Lomar® D (Diamond Shamrock Chemicals Co.); Daxad®19 andDaxad® K (W. R. Grace Co.); and Tamol® SN (Rohm & Haas). Representativeexamples of cationic surfactants include aliphatic amines, quaternaryammonium salts, sulfonium salts, phosphonium salts and the like.

Representative examples of nonionic dispersants or surfactants that canbe used in ink jet inks of the present invention include fluorinederivatives, silicone derivatives, acrylic acid copolymers,polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether,polyoxyethylene secondary alcohol ether, polyoxyethylene styrol ether,ethoxylated acetylenic diols (such as Surfynol® 420, Surfynol® 440, andSurfynol® 465, available from Air Products), polyoxyethylene lanolinderivatives, ethylene oxide derivatives of alkylphenol formalincondensates, polyoxyethylene polyoxypropylene block polymers, fatty acidesters of polyoxyethylene polyoxypropylene alkylether polyoxyethylenecompounds, ethylene glycol fatty acid esters of polyethylene oxidecondensation type, fatty acid monoglycerides, fatty acid esters ofpolyglycerol, fatty acid esters of propylene glycol, cane sugar fattyacid esters, fatty acid alkanol amides, polyoxyethylene fatty acidamides and polyoxyethylene alkylamine oxides. For example, ethoxylatedmonoalkyl or dialkyl phenols may be used, such as Igepal® CA and COseries materials (Rhone-Poulenc Co.), Brij® Series materials (ICIAmericas, Inc.), and Triton® series materials (Union Carbide Company).These nonionic surfactants or dispersants can be used alone or incombination with the aforementioned anionic and cationic dispersants.

The dispersing agents may also be a natural polymer or a syntheticpolymer dispersant. Specific examples of natural polymer dispersantsinclude proteins such as glue, gelatin, casein and albumin; naturalrubbers such as gum arabic and tragacanth gum; glucosides such assaponin; alginic acid, and alginic acid derivatives such aspropyleneglycol alginate, triethanolamine alginate, and ammoniumalginate; and cellulose derivatives such as methyl cellulose,carboxymethyl cellulose, hydroxyethyl cellulose and ethylhydroxycellulose. Specific examples of polymeric dispersants, includingsynthetic polymeric dispersants, include polyvinyl alcohols, such asElvanols from DuPont, Celvoline from Celanese, polyvinylpyrrolidonessuch as Luvatec from BASF, Kollidon and Plasdone from ISP, and PVP-K,Glide, acrylic or methacrylic resins (often written as “(meth)acrylic”)such as poly(meth)acrylic acid, Ethacryl line from Lyondell, Alcospersefrom Alco, acrylic acid-(meth)acrylonitrile copolymers, potassium(meth)acrylate-(meth)acrylonitrile copolymers, vinylacetate-(meth)acrylate ester copolymers and (meth)acrylicacid-(meth)acrylate ester copolymers; styrene-acrylic or methacrylicresins such as styrene-(meth)acrylic acid copolymers, such as theJoncryl line from BASF, Carbomers from Noveon, styrene-(meth)acrylicacid-(meth)acrylate ester copolymers, such as the Joncryl polymers fromBASF, styrene-α-methylstyrene-(meth)acrylic acid copolymers,styrene-α-methylstyrene-(meth)acrylic acid-(meth)acrylate estercopolymers; styrene-maleic acid copolymers; styrene-maleic anhydridecopolymers, such as the SMA polymers from Sartomer, vinylnaphthalene-acrylic or methacrylic acid copolymers; vinylnaphthalene-maleic acid copolymers; and vinyl acetate copolymers such asvinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinylethylene copolymers, vinyl acetate-maleate ester copolymers, vinylacetate-crotonic acid copolymer and vinyl acetate-acrylic acidcopolymer; and salts thereof. Polymers, such as those listed above,variations and related materials, that can be used for dispersants andadditives in inkjet inks are included in the Tego products from Degussa,the Ethacryl products from Lyondell, the Joncryl polymers from BASF, theEFKA dispersants from Ciba, and the Disperbyk and Byk dispersants fromBYK Chemie.

Humectants and water soluble organic compounds may also be added to theinkjet ink composition of the present invention, particularly for thepurpose of preventing clogging of the nozzle as well as for providingpaper penetration (penetrants), improved drying (drying accelerators),and anti-cockling properties. Specific examples of humectants and otherwater soluble compounds that may be used include low molecular-weightglycols such as ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol and dipropylene glycol; diols containing from about2 to about 40 carbon atoms, such as 1,3-pentanediol, 1,4-butanediol,1,5-pentanediol, 1,4-pentanediol, 1,6-hexanediol, 1,5-hexanediol,2,6-hexanediol, neopentylglycol (2,2-dimethyl-1,3-propanediol),1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,2,6-hexanetriol, poly(ethylene-co-propylene) glycol, and the like, aswell as their reaction products with alkylene oxides, including ethyleneoxides, including ethylene oxide and propylene oxide; triol derivativescontaining from about 3 to about 40 carbon atoms, including glycerine,trimethylolpropane, 1,3,5-pentanetriol, 1,2,6-hexanetriol, and the likeas well as their reaction products with alkylene oxides, includingethylene oxide, propylene oxide, and mixtures thereof; neopentylglycol,(2,2-dimethyl-1,3-propanediol), and the like, as well as their reactionproducts with alkylene oxides, including ethylene oxide and propyleneoxide in any desirable molar ratio to form materials with a wide rangeof molecular weights; thiodiglycol; pentaerythritol and lower alcoholssuch as ethanol, propanol, iso-propyl alcohol, n-butyl alcohol,sec-butyl alcohol, and tert-butyl alcohol, 2-propyn-1-ol (propargylalcohol), 2-buten-1-ol, 3-buten-2-ol, 3-butyn-2-ol, and cyclopropanol;amides such as dimethyl formaldehyde and dimethyl acetamide; ketones orketoalcohols such as acetone and diacetone alcohol; ethers such astetrahydrofuran and dioxane; cellosolves such as ethylene glycolmonomethyl ether and ethylene glycol monoethyl ether, triethylene glycolmonomethyl (or monoethyl) ether; carbitols such as diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, and diethyleneglycol monobutyl ether; lactams such as 2-pyrrolidone,N-methyl-2-pyrrolidone and ϵ-caprolactam; urea and urea derivatives;inner salts such as betaine, and the like; thio (sulfur) derivatives ofthe aforementioned materials including 1-butanethiol; t-butanethiol1-methyl-1-propanethiol, 2-methyl-1-propanethiol;2-methyl-2-propanethiol; thiocyclopropanol, thioethyleneglycol,thiodiethyleneglycol, trithio- or dithio-diethyleneglycol, and the like;hydroxyamide derivatives, including acetylethanolamine,acetylpropanolamine, propylcarboxyethanolamine, propylcarboxypropanolamine, and the like; reaction products of the aforementionedmaterials with alkylene oxides; and mixtures thereof. Additionalexamples include saccharides such as maltitol, sorbitol, gluconolactoneand maltose; polyhydric alcohols such as trimethylol propane andtrimethylol ethane; N-methyl-2-pyrrolidone;1,3-dimethyl-2-imidazolidinone; sulfoxide derivatives containing fromabout 2 to about 40 carbon atoms, including dialkylsulfides (symmetricand asymmetric sulfoxides) such as dimethylsulfoxide,methylethylsulfoxide, alkylphenyl sulfoxides, and the like; and sulfonederivatives (symmetric and asymmetric sulfones) containing from about 2to about 40 carbon atoms, such as dimethylsulfone, methylethylsulfone,sulfolane (tetramethylenesulfone, a cyclic sulfone), dialkyl sulfones,alkyl phenyl sulfones, dimethylsulfone, methylethylsulfone,diethylsulfone, ethylpropylsulfone, methylphenylsulfone,methylsulfolane, dimethylsulfolane, and the like. Such materials may beused alone or in combination.

Biocides and/or fungicides may also be added to the inkjet inkcomposition of the present invention. Biocides are important inpreventing bacterial growth since bacteria are often larger than inknozzles and can cause clogging as well as other printing problems.Examples of useful biocides include, but are not limited to, benzoate orsorbate salts, and isothiazolinones.

Various polymeric binders can also be used in conjunction with theinkjet ink composition of the present invention to adjust the viscosityof the composition as well as to provide other desirable properties.Suitable polymeric binders include, but are not limited to, watersoluble polymers and copolymers such as gum arabic, polyacrylate salts,polymethacrylate salts, polyvinyl alcohols (Elvanols from DuPont,Celvoline from Celanese), hydroxypropylenecellulose,hydroxyethylcellulose, polyvinylpyrrolidinone (such as Luvatec fromBASF, Kollidon and Plasdone from ISP, and PVP-K, Glide), polyvinylether,starch, polysaccharides, polyethyleneimines with or without beingderivatized with ethylene oxide and propylene oxide including theDiscole® series (DKS International); the Jeffamine® series (Huntsman);and the like. Additional examples of water-soluble polymer compoundsinclude various dispersants or surfactants described above, including,for example, styrene-acrylic acid copolymers (such as the Joncryl linefrom BASF, Carbomers from Noveon), styrene-acrylic acid-alkyl acrylateterpolymers, styrene-methacrylic acid copolymers (such as the Joncrylline from BASF), styrene-maleic acid copolymers (such as the SMApolymers from Sartomer), styrene-maleic acid-alkyl acrylate terpolymers,styrene-methacrylic acid-alkyl acrylate terpolymers, styrene-maleic acidhalf ester copolymers, vinyl naphthalene-acrylic acid copolymers,alginic acid, polyacrylic acids or their salts and their derivatives. Inaddition, the binder may be added or present in dispersion or latexform. For example, the polymeric binder may be a latex of acrylate ormethacrylate copolymers (such as NeoCryl materials from NSM Neoresins,the AC and AS polymers from Alberdingk-Boley) or may be a waterdispersible polyurethane (such as ABU from Alberdingk-Boley) orpolyester (such as AQ polymers from Eastman Chemical). Polymers, such asthose listed above, variations and related materials, that can be usedfor binders in inkjet inks are included in the Ethacryl products fromLyondell, the Joncryl polymers from BASF, the NeoCryl materials from NSMNeoresins, and the AC and AS polymers Alberdingk-Boley.

Various additives for controlling or regulating the pH of the inkjet inkcomposition of the present invention may also be used. Examples ofsuitable pH regulators include various amines such as diethanolamine andtriethanolamine as well as various hydroxide reagents. An hydroxidereagent is any reagent that comprises an OH⁻ ion, such as a salt havingan hydroxide counterion. Examples include sodium hydroxide, potassiumhydroxide, lithium hydroxide, ammonium hydroxide, and tetramethylammonium hydroxide. Other hydroxide salts, as well as mixtures ofhydroxide reagents, can also be used. Furthermore, other alkalinereagents may also be used which generate OH⁻ ions in an aqueous medium.Examples include carbonates such as sodium carbonate, bicarbonates suchas sodium bicarbonate, and alkoxides such as sodium methoxide and sodiumethoxide. Buffers may also be added.

Additionally, the inkjet ink composition of the present invention mayfurther incorporate conventional dyes to modify color balance and adjustoptical density. Such dyes include food dyes, FD&C dyes, acid dyes,direct dyes, reactive dyes, derivatives of phthalocyanine sulfonicacids, including copper phthalocyanine derivatives, sodium salts,ammonium salts, potassium salts, lithium salts, and the like.

The inkjet ink composition can be purified and/or classified usingmethods such as those described above for the modified pigments of thepresent invention. An optional counterion exchange step can also beused. Thus, unwanted impurities or undesirable large particles can beremoved to produce an ink with good overall properties.

It has surprisingly been found that inkjet ink compositions comprisingpolymers having the functional groups described above and, inparticular, comprising the modified colorants, preferably the modifiedpigments of the present invention, have improved overall propertiescompared to previously described inkjet ink compositions. While notwishing to be bound by theory, it is believed that the polymers havingthe described functional groups, particularly those with a calcium indexvalue as set forth above, when incorporated into the inkjet inkcompositions described above as either a separate additive or associated(attached or coated on) the colorant, produce stable dispersions thatrapidly destabilize when in contact with a substrate, such as paper. Thedestabilization may be a result of an interaction or binding withcalcium salts or other divalent metal salts present in the substrate orwhether subsequently added, such as by printing with a fixer fluidcontaining metal salts. Alternatively, or in addition, destabilizationmay result from a change in pH on contact with the substrate, which maybe particularly advantageous for modified pigments having the attachedpolymeric groups described above. It is believed that the rapiddestabilization after printing, caused either by a change in pH,interaction with calcium, or both, results in printed images with goodoverall properties, such as optical density, edge acuity, and/orintercolor bleed. Furthermore the polymer has been found to improve thedurability performance of printed images, including smear resistance,waterfastness, and/or rub resistance, in particular resistance tohighlighter pens.

The present invention further relates to an inkjet ink set whichcomprises various inkjet ink compositions and includes the inkjet inkcomposition of the present invention. The inkjet ink compositions ofthis set may differ in any way known in the art. For example, the inkjetink set may comprise inkjet ink compositions comprising different typesand/or colors of colorants, including, for example, an inkjet inkcomposition comprising a cyan pigment, an inkjet ink compositioncomprising a magenta pigment, and/or an inkjet ink compositioncomprising a black pigment. Other types of inkjet ink compositions mayalso be used, including, for example, compositions comprising agentsdesigned to fix the inkjet ink compositions onto the substrate. Othercombinations will be known in the art.

The present invention will be further clarified by the followingexamples, which are intended to be only exemplary in nature.

EXAMPLES Example 1

The following example describes the preparation of an inkjet inkcomposition comprising a liquid vehicle and a modified colorant of thepresent invention. In this example, the inkjet ink composition comprisesat least one colorant and at least one polymer prepared by thepolymerization of a monomer comprising a bisphosphonic acid group orsalts thereof.

Synthesis of a Bisphosphonate Monomer

A 1 L-3-neck round bottom flask was fitted with a thermometer and anaddition funnel. The flask was charged with a solution of 39 g of NaOHand 97.5 g of sodium alendronate (the monosodium salt of a4-amino-1-hydroxybutane-1,1-diyl)bisphosphonic acid, commerciallyavailable from Zentiva, Prague, Czech Republic) in 600 g of water. Thesolution was stirred and cooled down to approximately 5° C. using an icebath. Methacryloyl chloride (39.3 g) was added dropwise via the additionfunnel while keeping the temperature below 10° C. The reaction wasstirred for 20 minutes. To this was added 37% HCl (approximately 44 g)until the pH decreased to approximately 3.4. The solution was thenextracted with dichloromethane (3×300 mL). The aqueous phase was mixedwith approximately 3 L of Ethanol, and the desired bisphosphonatemonomer product precipitated as a white solid, which was collected byfiltration and dried in a vacuum oven at 60° C.

Synthesis of a Polymer

A copolymer was prepared using semi-continuous feed techniques. In a 500mL three-neck round-bottom flask equipped with an addition funnel, athermocouple, and a rubber septum was charged with 60 mL DMF, and thetemperature was increased and maintained at 100° C. The addition funnelwas charged with a solution of a mixed monomer solution of2-hydroxypropyl acrylamide (15 g) and t-octylacrylamide (27.5 g) in 50mL of DMF. Two other feed streams were dispensed from syringes throughthe septum. One feed stream contained a solution of the bisphosphonatemonomer described above (7.5 g) in 30 mL water, to which water was addedover the course of the polymerization as needed in order to maintainsolubility. The second feed stream was an initiator solution of benzoylperoxide (1.5 g) in 25 mL DMF. Ten percent of each feed stream was addedto the reaction flask. After thirty minutes, 1/12 of the initiatorsolution and the mixed monomer solution were added. After another thirtyminutes, 1/12 of all three feed streams were added, and this continued,maintaining the temperature, for another 5 hours. At the end of thereaction, the last 1/12 of the bisphosphonate monomer solution wasadded. The reaction was maintained for an additional hour before coolingto room temperature. The resulting polymer precipitated during thereaction, and was isolated by pouring off the supernatant. The solidswere rinsed with hexanes to drive off the high-boiling DMF and driedunder vacuum for 14 hours. The polymer, comprising repeating unitshaving bisphosphonate groups, was used as is for the preparation of aninkjet ink composition.

Modified Colorant

A pigment comprising at least one polymer was prepared by adding to anEiger 1 H Laboratory vessel (5.5 inch diameter stainless steel beaker)9.5 g of Black Pearls® 700 carbon black (commercially available fromCabot Corporation), a solution of 11.4 g of polymer above and 100 mL ofNMP, and 2000 g of Norstone milling media (BSLZ-1 0.07-0.125 mm,commercially available from Norstone, Wyncote, Pa.). The mixture wasmilled at 5000 rpm, with addition of NMP as needed to keep the mixturefluid, for 20 minutes. To this was added 6.66 g of a 10% aqueous sodiumhydroxide solution, along with 500 mL of deionized water, and millingwas continued for an additional 15 minutes. The mixture, which containedthe pigment comprising a polymer, was filtered to remove the millingmedia. The resulting dispersion had a total volume of 3 L, including thewater used to rinse the milling media.

This dispersion was concentrated to 300 mL by diafiltration using aSpectrum Membrane (1050 cm²) and a peristaltic pump. The dispersion wasfurther purified by diafiltration with 10 volumes nanopure water. Thedispersion was sonicated for an hour using a Misonix 3000 sonicatorusing the microtip at power 5.5, and a pulse cycle of 8 seconds on, 2seconds rest. The resulting dispersion of the modified colorant, whichis a pigment comprising at least one polymer (16.07% solids) was foundto have a mean volume particle size (mV), determined using a Microtrac®Particle Size Analyzer, of 160 nm.

The amount of polymer coated on the pigment was determined by comparingthe UV/Vis absorbance of the polymer-coated pigment in a dispersion of aknown concentration to that of a dispersion of the starting pigment atthe same concentration, using a wavelength where the pigment absorbs.For the modified colorant used in this example, a wavelength of 550 nmwas chosen for absorbance measurements on the UV/Vis Spectrophotometer.The extinction coefficient for both the polymer-coated pigment and thestarting pigment will be the same. Since both dispersions are at thesame concentration, any observed decrease in absorbance must be due to adifference in the actual amount of pigment in the polymer-coated pigmentdispersion. This difference is the amount of polymer present and can bereported as % polymer. For the colorant composition of this example, theamount of polymer coated on the pigment was found to be 38.68% polymerby this UV method. This modified colorant was used to prepare an inkjetink composition of the present invention.

Inkjet Ink Compositions

An inkjet ink composition of the present invention was prepared usingthe formulation shown in Table 1 below.

TABLE 1 Component Amount Dispersion of Modified Colorant 13.69 gGlycerol 3 g 1,2-hexanediol 1.5 g Surfynol 465 0.3 g Water 11.51 gThis inkjet ink composition was loaded into an Epson compatiblecartridge (available from Inkjet Warehouse, black cartridge part numberE-0601-K) and printed using an Epson C88 printer with print settings“plain paper/best photo/ICM off”.

Print performance properties were determined for the resulting printedimages. Optical density was measured using a SpectroEyeSpectrodensitometer. The settings used were used: Illumination at D65, 2degree standard observer, DIN density standards, white base set to Abs,and no filter. Results are reported as an average of three opticaldensity measurements taken at two corners, and the middle of a page.Smear resistance was measured on high optical density stripes using ayellow Avery Fluorescent Hi-Lighter™ Chisel Point #111646 and an orangeACCENT™ Highlighter Fluorescent Chisel Tip #25006. For each highlighter,two swipes were made on an unprinted section of paper, and then twoswipes were made across three 2 mm wide stripes printed 2 mm apart usingthe specified inkjet ink composition. The highlighter pen was cleanedbetween swipes on a piece of scrap paper. Smear resistance was visuallyevaluated to assess visible evidence of smearing from the printed stripewithin the highlighter swipe: “yes”=noticeable smearing is observed,“trace”=a slight amount of smearing is seen, and “no”=no smearing isfound.

Images printed on Hammermill Copy Plus paper were found to have on OD of1.4, and no smear was observed. Thus, the inkjet ink composition of thepresent invention has good overall performance, with a balance of highOD and high smear resistance.

Example 2

The following example describes the preparation of an inkjet inkcomposition comprising a liquid vehicle and a modified colorant of thepresent invention. In this example, the inkjet ink composition comprisesat least one colorant and at least one polymer prepared by thepolymerization of a monomer comprising a benzene tricarboxylic acidgroup or salts thereof.

Synthesis of a Benzene Tricarboxylic Acid Monomer

To a 2 L three-neck round bottom flask equipped with a magnetic stirbar, thermometer, and a 250 mL addition funnel was charged 1 L water and71 g sodium hydroxide pellets. When this had dissolved, 100 g of1-aminobenzene-3,4,5-tricarboxylic acid was added, which also dissolved.When the heat of neutralization dissipated, the reaction was cooled to10° C. with an ice bath. Methacryloyl chloride (40.23 g) was charged tothe addition funnel. This was added to the reaction vessel dropwise,over fifteen minutes, maintaining a temperature of less than 15° C. In aseparate vessel, 40 g of sodium hydroxide was dissolved in 150 g water.This was added to the reaction mixture 20 minutes after the methacryloylchloride addition was complete. Once the reaction had cooled to 10° C.,an additional 40 g of methacryloyl chloride was added dropwise from theaddition funnel over fifteen minutes, keeping the temperature under 15°C. Twenty minutes after the addition was complete, the reaction mixturewas acidified to a pH of 3 with concentrated HCl. The resulting solidswere collected by vacuum filtration, washed with ethanol, and dried in avacuum oven at 60° C. for 14 hours.

Synthesis of a Polymer

A copolymer was prepared using modified semi-continuous feed techniques.The acrylamido-benzenetricarboxylic acid monomer described above wasdissolved (7% solids) in DMSO by stirring 14 hours with acidic Amberliteresin that was first washed with DMSO to remove impurities. Into thissolution, butyl acrylate and nitrophenyl acrylamide were dissolved, sothat the weight ratios of the monomers were 28.7 weight percentacrylamido-benzenetricarboxylic acid monomer, 68.3 weight percent butylacrylate and 3 weight percent nitrophenyl acrylamide. A small amount (3%by weight based on total monomer feed) of mesitylene was also added toserve as an internal standard for NMR analysis. One tenth of thesolution was charged to a three-neck, round-bottom flask equipped with athermostatted heating mantle with thermocouple, an addition funnel, anda septum-capped ground-glass joint. The balance of the solution wascharged to the addition funnel. 3% by weight on total monomer of4,4′-azobiscyanovaleric acid (ACVA), dissolved at 10% solids in DMSO wascharged to a hypodermic syringe. The reaction mixture was heated to 105°C., and one tenth of the ACVA solution was added to the reactionmixture. One tenth of the remaining monomer solution, and remaininginitiator solution, was added every half an hour for five hours, afterwhich the temperature was maintained at 105° C. for one hour, and thenallowed to cool. The resulting polymer, comprising repeating unitshaving benzenetricarboxylic acid groups, was collected by precipitationinto 5% by weight acetic acid in water, and washing the solids twicewith distilled water. The inherent viscosity of the polymer was 0.066dL/g in THF, and the acid number was 131 mg/KOH polymer.

The polymer was hydrogenated in THF solution (10% solids) by firstpurging with nitrogen for 10 min. To the above solution 10% palladium oncarbon catalyst (2.5 g) was added and the mixture was hydrogenated onParr apparatus at 45 psi for 3-4 hours. The resulting polymer was usedas is for the preparation of an inkjet ink composition.

Modified Colorant

To a 500 mL stainless steel beaker was added 20 g Black Pearls® 700carbon black. The polymer described above (20 g) was dissolved in 132 gTHF, and the resulting solution along with 48 g THF and 20 g water wereadded to the carbon black in the stainless steel beaker. This mixturewas agitated with a propeller blade and a rotor-stator, and heated to atemperature of 55° C. In a separate vessel 0.25 g sodium nitrite wasdissolved in 16 g of water. Methanesulfonic acid (0.35 g) was added tothe agitating mixture, and the sodium nitrite solution was addeddropwise over 5 minutes. The mixture was maintained at 55° C. withagitation for 2 hours. The reaction mixture was then added to apolyethylene vessel containing 800 mL of THF with manual agitation. Theresulting solids were collected by centrifugation and washed twice withTHF. The solids were dispersed in 500 mL water at pH 9 with a sonicprobe for 30 minutes. The resulting dispersion was classified by passingthrough a 20 micron screen, and diafiltered with 10 volumes of water(approximately 5 liters). The resulting dispersion of modified colorant,which is a pigment comprising at least one polymer was found to have amean volume particle size (mV), determined using a Microtrac® ParticleSize Analyzer, of 192 nm, and. The modified pigment was found to have12.1% volatiles, determined by TGA.

Comparative Modified Colorant

Black Pearls® 700 carbon black (500 g), 81 g of1-amino-3,4,5-benzenetricarboxylic acid, and 650 g of water was chargedto a ProcessAll 4HV Mixer (4 liter) which was held at 50° C. The mixerwas sealed and agitation was started (300 RPM). In a separate vessel,17.28 g sodium hydroxide was dissolved in 200 g of water. This sodiumhydroxide solution was added to the mixer during agitation. In a thirdvessel 24.84 g sodium nitrite was dissolved in 75.16 g water. When thecontents of the mixer were at 50° C., the sodium nitrite solution waspumped into the mixer over 15 minutes. The temperature and agitationwere maintained for two hours. At the end of the 2 hours, the mixer wasopened, and 61 g of 4-aminobenzyl amine were added. The mixer was sealedand agitated for five minutes, after which the vessel was again openedand a further 61 g of 4-aminobenzyl amine was added. The sealed mixturewas agitated another ten minutes. In a separate vessel, 180 g of 70%aqueous nitric acid was mixed with 180 g water, and this solution waspumped into the agitated vessel over five minutes. The pump line wasrinsed with 50 mL water, and agitation was maintained for 15 minutes,during which the temperature was raised to 60° C. In another vessel 69 gof sodium nitrite were dissolved in 276 g water, and this sodiumnitirite solution was pumped into the mixer over 15 minutes. Thetemperature and agitation were maintained for two hours, and then 200 gwater was added and mixed for fifteen minutes. The resulting slurry wasremoved from the mixer, and the mixer was rinsed twice with 1 L ofwater, with each rinse being added to the slurry, resulting in 4,645 gof slurry. One half of this, approximately 2,323 g was diluted withwater to a volume of 3.5 L and stirred with a paddle blade for 20minutes. This slurry was filtered with a Buchner funnel and Whatman 1filter paper, slurried with fresh water, and recombined with theunwashed slurry, resulting in a dispersion that was 11.88% solidscomprising a modified pigment having attached benzene tricarboxylic acidgroups.

Inkjet Ink Compositions

The dispersion of the modified colorant of the present invention and thecomparative modified colorant were used to make inkjet ink compositionscontaining 4% carbon black (with solids at 4.2-4.6%), 7% glycerin, 7%trimethylolpropane, 5% diethylene glycol, 1% Surfynol® 465 surfactantwith the balance as water. These inks were loaded into cartridges andprinted with a Canon I550 printer onto four different papers—HammermillCopy Plus (HCP), Hammermill Premium Inkjet (HPI), Xerox 4200 and HPBright White (HPBW). The resulting images were evaluated for opticaldensity (measured using ImageXpert™) and resistance to highlighter smear(“good” means little or no smear and “poor” means a significant amountof visible smear), and the results are shown in Table 2 below.

TABLE 2 Highlighter resistance Modified Pigment Average OD Orange YellowExample 2 1.33 Good Good Comparative Colorant 1.35 Poor PoorAs the results show, the inkjet ink composition of the presentinvention, comprising a modified pigment which comprises a pigment andpolymer having an aryl tricarboxylic acid group, produces printed imageshaving comparable OD to printed images produced from an inkjet inkcomposition comprising a modified pigment which comprises a pigmenthaving attached a similar organic group but no polymeric group. However,improved highlighter resistance was observed for images from the inkjetink composition of the present invention. Thus, these inkjet inkcompositions have good balance of OD and highlighter resistance.

Example 3

The following example describes the preparation of an inkjet inkcomposition comprising a liquid vehicle, a modified pigment, and apolymer having at least two phosphonic acid groups, or salts thereof.

In a 1 L Erlenmeyer flask was added 100 g of Joncryl 683 (a styreneacrylate copolymer available from BASF, total acid of 295 mmol) and 25.4g of N-hydroxysuccinimide (HOSI, 220 mmol, 0.75 eq. of available acidgroup of the polymer) in 600 mL of anhydrous THF. The solution wasstirred at ambient temperature while 45 g ofN,N′-dicyclohexyl-carbodiimide (DCC, 20 mmol, 0.75 eq.) in 100 mL of THFwas added slowly. After stirring at room temperature overnight, themixture was filtered to remove the dicyclohexylurea (DCU) precipitateand the resulting activated Joncryl polymer solution was used withoutfurther purification.

214.18 g of a 11.67% solids dispersion of Pigment Red 122 modified with4-aminobenzylamine (4-ABA, 2 mmol/g treatment level) was added to a 1 Lstainless steel beaker. To this was added 15.04 g of alendronate sodium(the monosodium salt of a 4-amino-1-hydroxybutane-1,1-diyl)bisphosphonicacid, commercially available from Zentiva, Prague, Czech Republic). Thesample was mixed with a Silverson L4RT mixer at 6000 RPM for 15 minutes.

Next, 87.53 g (at 28.5% solids) of the activated Joncryl polymersolution was added to the mixture, and the pH was adjusted toapproximately 8.5-9.0 with a 2M NaOH solution. The material was mixedwith a Silverson mixer for 3 hours at 7000-7500 RPM at 50°−60° C.Continuous addition of 2M NaOH solution was used to maintain the pH at8.5-9.0 during the 3 hours. The mixture was then pH adjusted to 10 witha 2M NaOH solution and mixed for another 1 hour at 60° C. whilemaintaining pH. Also, 2-ethyl-1-hexanol could periodically be added tocontrol foaming.

The pigment mixture was sonicated using a Misonix sonic probe at themaximum setting for 1 hour, filtered through a 45 μm sieve, anddiafiltered with 0.0001M NaOH at 400 mL/volume for 10 volumes. Thedispersion was then diafiltered with DI H₂O at 400 mL/volume for 10volumes, and sonicated using the sonic probe for 2 hours at setting 10.The sample was then centrifuged for 40 minutes at 4500 RPM, yielding ared pigment dispersion having a solids level of 12.33%, a sodium levelmeasured by sodium probe of 13535 ppm/solids, and a polymer attachmentlevel measured as described in Example 1 of 50.53% based on the totalweight of the modified pigment.

It would be expected that this dispersion could be used in an inkjet inkcomposition. Furthermore, the dispersion comprises both a polymer havinga bisphosphonic acid functional group as well as a modified red pigmentcomprising a red pigment having attached at least one polymeric group,wherein the polymeric group comprises this polymer. This is because boththe starting modified red pigment (having an attached amine group) andthe alendronate sodium (also having an amine group) would be expected tocompete for the activated Joncryl polymer. Therefore, using theresulting modified red pigment dispersion would be expected to producean inkjet ink composition of the present invention, comprising a liquidvehicle, a modified pigment, and a polymer having at least onefunctional group comprising a bisphosphonic acid group, or salt thereof.

Example 4

This example describes methods for determining calcium index values.

Method A

For this method, a series of solutions were prepared at pH 9 thatcontained 0.087 mM Congo Red indicator, 5 mM cesium chloride, 1 wt %MW350 polyethylene glycol methyl ether, and calcium chloride inconcentrations ranging from 0 to 7 mM (0.2, 0.5, 1, 2, 3, 4, 4.5, 5, 6,and 7 mM). The UV-Vis spectra of these solutions were recorded within 1hour of their preparation using a UV-2501PC. These spectra were used tocreate a calibration curve relating the absorbance at 520 nm to thecalcium concentration.

A compound was then chosen that corresponds to a specific organic groupattached to a polymer. For example, for a modified carbon blackcomprising a polymer having attached a 3,4,5 tricarboxyphenyl group orsalts thereof, 1,2,3-benzene tricarboxylic acid would be chosen. Testsolutions were then prepared at pH 9 that contained 0.087 mM Congo Redindicator, 1 wt % MW350 polyethylene glycol methyl ether, 5 mM calciumchloride, and the cesium salt of the compound of interest such that theion concentration at pH 9 was 5 mM. The uncomplexed calciumconcentration was determined by comparison with the calibration curve.The calcium index value was then calculated as log₁₀((0.005−uncomplexedcalcium)/((uncomplexed calcium)²)). Measurements were made in duplicateand averaged.

Using this method, the calcium index values of various compounds,relating to the organic groups of modified pigments comprising pigmentshaving these organic groups attached, were determined and are shown inTable 3A below.

TABLE 3A Compound Calcium index value Toluene sulfonic acid 0.78 benzoicacid 1.27 isophthalic acid 1.76 phthalic acid 2.051,1,1-trifluoro-2,4-pentanedione 2.33 succinic acid 2.37 benzohydroxamicacid 2.43 1,2,4-benzene tricarboxylic acid 2.53 Benzenephosphonic acid2.53 malonic acid 2.58 1,2,3-benzene tricarboxylic acid 2.792,3-dihydroxypyridine 3.06 8-hydroxyquinoline 3.08 2-hydroxypyridineoxide 3.27 methylene diphosphonic acid 3.45Thus, as the data in Table 3A shows, compounds such as 2-hydroxypyridineN-oxide (1-hydroxy pyridone), 8-hydroxyquinoline, and methylenediphosphonic acid have calcium index values greater than that of1,2,3-benzene tricarboxylic acid. These also have calcium index valuesgreater than or equal to that of benzene phosphonic acid(phenylphosphonic acid), as do compounds such as 1,2,4-benzenetricarboxylic acid and malonic acid. Compounds comprising these orsimilar groups, such as other bisphosphonates or groups having at leasttwo phosphonic acid groups, partial esters thereof, or salts thereof,would also be expected to have similarly high calcium index values.Method B

For compounds which develop a high level of color and are thereforedifficult to use in Method A, a second method was developed. For thismethod, an aqueous solution that was 0.01M in ⁴³CaCl₂, 0.01M in NaCl,10% D₂O and at pH 8 or 9 was prepared from ⁴³CaCO₃, HCl/D₂O, NaOH/D₂O,D₂O and water. The pH was chosen to ionize the compound underinvestigation and to dissolve the compound. A portion of the solutionweighing about 0.65 g was added to a 5 mm NMR tube and weighed to thenearest 0.001 g. The chemical shift of the unbound ⁴³Ca was measuredusing a Bruker Avance II spectrometer with a proton resonance frequencyat 400.13 MHz. A 0.2-1.0M solution of the compound (ligand) underinvestigation was added in successive increments. After each addition,the ⁴³Ca chemical shift was measured, and δ, the difference between thechemical shift of the sample and that of unbound calcium was calculated.The successive increments were planned such that the L_(o)/Ca_(o) ratiowas 0.25, 0.5, 1, 2, 3, 4, 6 and 8 where L_(o) is the totalconcentration of complexed, protonated and free anions from the ligandand Ca_(o) is the total concentration of calcium in all species present.The calcium binding index (NMR) was calculated as log₁₀(X) where X wasdetermined by fitting the parameters X and δ_(m) in the equation

$\delta = {\frac{\delta_{m}}{2}\left\{ {\left\lbrack {1 + \left( {L_{0}/{Ca}_{0}} \right) + {\left( {1 + {H^{+}/K_{a}}} \right)/\left( {X\;{Ca}_{0}} \right)}} \right\rbrack - \sqrt{\left\lbrack {1 + \left( {L_{0}/{Ca}_{0}} \right) + {\left( {1 + {H^{+}/K_{a}}} \right)/\left( {X{Ca}}_{0} \right)}} \right\rbrack^{2} - {4\left( {L_{0}/{Ca}_{0}} \right)}}} \right\}}$so that the RMS difference between the data and the predicted chemicalshifts from the equation are minimized where

δ is the difference in the ⁴³Ca chemical shift of the sample vs that offree aqueous ⁴³Ca²⁺

δ_(m) is the calculated difference in the ⁴³Ca chemical shift atinfinite L/Ca vs that of free ⁴³Ca²⁺

L_(o) is the total concentration of complexed, protonated and freeanions from the ligand

Ca_(o) is the total concentration of calcium in all species present

X is a fitting parameter

K_(a) is the proton dissociation constant for the ligand LH

Using this method, the calcium index values of various compounds,relating to the organic groups of modified pigments comprising pigmentshaving these organic groups attached, were determined and are shown inTable 3B below.

TABLE 3B Compound Calcium index value benzoic acid 0.58 1,2,3-benzenetricarboxylic acid 1.99 2-chloro-4-methyl-6-nitrosophenol 2.22The calcium index values by Method B are different than those done byMethod A and cannot be compared directly with them.

Example 5

The following example describes a method for the preparation of apolymer that can be used for preparing a modified colorant and/or andinkjet ink composition of the present invention.

Synthesis of an Initiator

4,4′-Azobis(4-cyanovaleric acid) (10 g, 35 mmol) was added to thionylchloride (20 ml). The reaction mixture was refluxed at 80° C. for 40 minor until solids are completely dissolved. The hot solution was immersedin an ice bath and cooled to room temperature. The solution was pouredinto cold hexane (200 ml) and stirred for 4 hours at 5° C. to allowproduct to precipitate. The precipitate was filtered and washed withcold hexane (200 ml) to yield 4,4′-azobis(4-cyanovaleric acid chloride)as a white solid (11.2 g, 99%).

p-Phenylenediamine (8.47 g, 78 mmol) was dissolved in dry THF (500 ml)and triethylamine (7.92 g, 78 mmol) was added. The reaction mixture wascooled to 5° C. using ice/water bath. A solution of4,4′-azobis(4-cyanovaleric acid chloride) (11.2 g, 35 mmol) in 100 mlTHF was added dropwise to the above mixture over 0.5 hour.

After the addition was complete, the reaction mixture was stirred foranother 2 hours at 0-5° C. The precipitate (triethylamine hydrochloride)was filtered off and washed with 200 ml of THF. The filtrate waspartially concentrated (about half of the solvent was evaporated), anddiluted with water (300 mL). 37% HCl is added to the solution until pHdecreased to 2. The resulting solution was washed with ethyl acetate(2×200 ml), and the pH of the aqueous layer was adjusted to 5 using 40%NaOH. The resulting solution was extracted with ethyl acetate (2×300ml), and the combined organic layers were concentrated to yield4,4′-azobis(N-p-aminophenyl-4-cyanovaleramide) (4.0 g, 25% yield).

Synthesis of a Bisphosphonate Monomer

A tetrabutyl ammonium cation exchange resin is prepared by stirring a5-fold molar excess of tetrabutyl ammonium hydroxide with a proticexchange resin for 14 hours, at 60° C. The resulting tetrabutyl ammoniumresin was washed until the pH of the rinse water is 7. This resin wasthen stirred with the bisphosphonate monomer of Example 1, 10% by weightin water, in a 10-fold molar excess at 80° C. for 14 hours. Theresulting salt, tris(tetrabutyl ammonium) alondronate methacrylamide,was recovered by washing the resin with 10 volumes of water, andevaporating the water.

Synthesis of a Polymer

A copolymer was prepared by dissolving 10 g of the above tris(tetrabutylammonium) alondronate methacrylamide, 1.71 g of isopropyl acrylamide,8.29 g of butyl acrylate, 1.0 g of octanone (internal standard for GC),and 0.08 g aminothiphenol in 50 mL dimethylformamide, giving a totalvolume of 75 mL. Dimethylformamide (6 mL) was charged to a 250 mL roundbottom flask equipped with a spin bar, a nitrogen inlet, an additionfunnel, and a septum. The temperature was termostatted at 95-96° C. forthe duration of the reaction. The DMF solution of monomers was chargedto the addition funnel. 4,4′-azobis(N-p-aminophenyl-4-cyanovaleramide,prepared above, (0.2 g) was dissolved in 9.5 mL DMF, and charged to ahypodermic syringe, which was inserted into the septum-capped port ofthe reaction vessel. Twenty percent of the total volume of the additionfunnel (ca 15 mL) was added to the reaction vessel. At the same time, 1mL of the initiator solution was added. Additions were carried outaccording to the schedule shown in Table 4 below:

TABLE 4 Time (hr) Monomer solution added Initiator added 0 15 1 1 9 0.53 0 0.5 4 0 0.5 5 0 0.5 6 0 0.5 7 9 0.5 8 8 0.5 9 9 0.5 10 7 0.5 10.5 50.5 11 5 0.5 11.25 0 0.5

After the additions were complete, the reaction mixture was allowed tocool to room temperature. The reaction mixture was subjected to rotoraryevaporation to remove any unreacted butyl acrylate, and then 1 mL of thereaction mixture was diluted with 5 mL of water and placed in a dialysisbag (MW cutoff 1000) and dialyzed against 50 mM sodium nitrate solutionfor 14 hours, then against distilled water for 24 hours. The resultingsolution was 0.56% solids, and the polymer was found to be 3% by weightphosphorous, corresponding to 60 meq ionic charge/g polymer. Thispolymer solution could be used without further purification forpreparing a modified colorant, such as a modified pigment, of thepresent invention as well as an inkjet ink composition of the presentinvention.

The foregoing description of preferred embodiments of the presentinvention has been presented for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise form disclosed. Modifications and variationsare possible in light of the above teachings, or may be acquired frompractice of the invention. The embodiments were chosen and described inorder to explain the principles of the invention and its practicalapplication to enable one skilled in the art to utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto, and theirequivalents.

What is claimed is:
 1. A modified colorant comprising a pigment and apolymer having at least one functional group having a calcium indexvalue greater than or equal to a calcium binding index value of1,2,3-benzene tricarboxylic acid, wherein the polymer is a coating onthe pigment, wherein the functional group comprises at least one geminalbisphosphonic acid group, partial esters thereof, or salts thereof, andwherein the polymer comprises at least one monomer comprising thefunctional group.
 2. The modified colorant of claim 1, wherein thefunctional group comprises at least one group having the formula—CQ(PO₃H₂)₂ or salts thereof, wherein Q is H, R, OR, SR, or NR₂ whereinR, which can be the same or different, is H, a C₁-C₁₈ alkyl group, aC₁-C₁₈ acyl group, an aralkyl group, an alkaryl group, or an aryl group.3. The modified colorant of claim 2, wherein the functional groupcomprises at least one group having the formula —(CH₂)_(n)—CQ(PO₃H₂)₂ orsalts thereof, wherein n is 1 to
 9. 4. The modified colorant of claim 3,wherein n is 1 to
 3. 5. The modified colorant of claim 2, wherein thefunctional group comprises a group having the formula-Sp-(CH₂)₂—CQ(PO₃H₂)₂ or salt thereof, wherein Sp is a spacer group andwherein n is 0 to
 9. 6. The modified colorant of claim 5, wherein Sp is—CO₂—, —O₂C—, —O—, —NR″—, —NR″CO—, —CONR″—, —SO₂CH₂CH₂NR″—,—SO₂CH₂CH₂O—, or —SO₂CH₂CH₂S—, wherein R″ is H or a C₁-C₆ alkyl group.7. The modified colorant of claim 1, wherein the functional groupcomprises at least one group having the formula —N—[(CH₂)_(m)(PO₃H₂)]₂or salts thereof, wherein m, which can be the same or different, is 1 to3.
 8. The modified colorant of claim 7, wherein the functional groupcomprises at least one group having the formula—(CH₂)_(n)—N—[(CH₂)_(m)(PO₃H₂)]₂ or salts thereof, wherein n is 1 to 9.9. The modified colorant of claim 7, wherein the functional groupcomprises a group having the formula -Sp-(CH₂)_(n)—N—[(CH₂)_(m)(PO₃H₂)]₂or salts thereof, wherein Sp is a spacer group and wherein n is 0 to 9.10. The modified colorant of claim 9, wherein Sp is —CO₂—, —O₂C—, —O—,—NR″—, NR″CO—, —CONR″—, —SO₂CH₂CH₂NR″—, —SO₂CH₂CH₂O—, or —SO₂CH₂CH₂S—,wherein R″ is H or a C₁-C₆ alkyl group.
 11. The modified colorant ofclaim 1, wherein the functional group comprises at least one grouphaving the formula —CR═C(PO₃H₂)₂ or salts thereof, wherein R is H, aC₁-C₆ alkyl group, or an aryl group.